Implantable medical device including assembly incorporating radiopaque agent and elutable drug into a polymeric lead tip

ABSTRACT

An assembly for an implantable device can be made from PEEK and can incorporate one or more radiopaque agents and one or more elutable drug components into a polymeric lead tip. The assembly can be machined or injection molded and can be configured, for example, as a housing for an active fixation lead or as an electrode base supporting a foil electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(e) to U.S.Provisional Application 61/769,555, filed on Feb. 26, 2013, which isherein incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to implantable medical devices and relatesmore particularly to leads for cardiac rhythm management (CRM) systems.

BACKGROUND

Various types of medical electrical leads for use in CRM andneurostimulation systems are known. For CRM systems, such leads aretypically extended intravascularly to an implantation location within oron a patient's heart, and thereafter coupled to a pulse generator orother implantable device for sensing cardiac electrical activity,delivering therapeutic stimuli, and the like. The leads frequentlyinclude features to facilitate securing the lead to heart tissue tomaintain the lead at its desired implantation site.

SUMMARY

Example 1 is an implantable lead having a flexible body, a connectorassembly secured to a proximal end of the flexible body for coupling toan implantable medical device and a distal assembly coupled to a distalend of the flexible body. The connector assembly includes a terminal pinthat is rotatable relative to the body. A conductor member is disposedlongitudinally within the body and is rotatable relative to the body,and is coupled to the terminal pin. The distal assembly includes ahousing having a proximal region that is fixedly coupled the distal endof the body. The housing is formed from a polymeric material. Aradiopaque agent is dispersed within the polymeric material. An elutabledrug component is dispersed within the polymeric material. A couplerhaving a proximal end is connected at its proximal end to the conductormember, the coupler being rotatably disposed within the housing. Ahelical electrode is fixedly secured to the coupler. The terminal pin isrotatably engaged with the coupler via the conductor member such thatrotation of the terminal pin causes the coupler and the helicalelectrode to rotate and therefore translate relative to the housing.

Example 2 includes Example 1 and specifies that the polymeric materialincludes polyetheretherketone.

Example 3 includes Examples 1 and 2 and specifies that the housingincludes an at least substantially homogenous mixture of radiopaqueagent, elutable drug component and polyetheretherketone.

Example 4 includes Examples 1 through 3 and specifies that the polymericmaterial forming the housing includes about 5 to about 80 weight percentradiopaque agent, about 1 to about 50 weight percent elutable drugcomponent and a balance polyetheretherketone.

Example 5 includes Examples 1 through 4 and specifies that the polymericmaterial forming the housing includes about 30 to about 70 weightpercent radiopaque agent, about 10 to about 35 weight percent elutabledrug component and a balance polyetheretherketone.

Example 6 includes Examples 1 through 5 and specifies that the polymericmaterial forming the housing includes about 40 to about 60 weightpercent radiopaque agent, about 15 to about 25 weight percent elutabledrug component and a balance polyetheretherketone.

Example 7 includes Examples 1 through 6 and specifies that theradiopaque agent includes one or more of barium sulfate, bariumtrioxide, tungsten, platinum, iridium and alloys thereof.

Example 8 includes Examples 1 through 7 and specifies that the elutabledrug component includes a steroid.

Example 9 is an implantable lead that is configured to carry anelectrical signal. The implantable lead includes a flexible bodyextending between a proximal portion and a distal portion, the bodyconfigured to carry an electrical signal from the proximal portion tothe distal portion. An assembly is coupled to the distal portion of theflexible body, the assembly formed from an at least substantiallyhomogenous combination of polyetheretherketone, radiopaque agent andelutable drug component.

Example 10 includes Example 9 and specifies that the assembly includes ahousing extending from the distal portion of the flexible body, theimplantable lead further including a coupler that is disposed within thehousing and a fixation helix that is secured to the coupler.

Example 11 includes Example 9 and specifies that the implantable leadfurther includes a foil electrode, and the assembly is an electrode basethat is configured to support the foil electrode.

Example 12 includes Example 11 and specifies that the electrode base hasan outer surface having a first region and a second region, the firstregion supporting the foil electrode and the second region uncovered topermit drug elution from the electrode base.

Example 13 includes Examples 9 through 12 and specifies that theassembly includes about 5 to about 80 weight percent radiopaque agent,about 1 to about 50 weight percent elutable drug component and a balancepolyetheretherketone.

Example 14 includes Examples 9 through 13 and specifies that theassembly includes about 30 to about 70 weight percent radiopaque agent,about 10 to about 35 weight percent elutable drug component and abalance polyetheretherketone.

Example 15 includes Examples 9 through 14 and specifies that theassembly includes about 40 to about 60 weight percent radiopaque agent,about 15 to about 25 weight percent elutable drug component and abalance polyetheretherketone.

Example 16 includes Examples 9 through 15 and specifies that theradiopaque agent includes one or more of barium sulfate, bariumtrioxide, tungsten, platinum, iridium and alloys thereof.

Example 17 includes Examples 9 through 16 and specifies that theelutable drug component includes one or more of dexamethasone,betamethasone, paramethasone, beclomethasone, clobetasol, triamcinolone,prednisone, prednisolone and derivatives thereof.

Example 18 is an implantable lead that is configured to carry anelectrical signal. The lead includes a flexible body extending between aproximal portion and a distal portion, the body configured to carry anelectrical signal from the proximal portion to the distal portion. Anelectrode base is coupled to the distal portion of the flexible body anda foil electrode is supported by a portion of the electrode base. Theelectrode base is formed from an at least substantially homogenouscombination of polyetheretherketone, radiopaque agent and elutable drugcomponent.

Example 19 includes Example 18 and specifies that the electrode base hasan outer surface having a first region and a second region, the firstregion having a first diameter and supporting the foil electrode and thesecond region having a second diameter greater than the first diameter,the second region uncovered to permit drug elution from the electrodebase.

Example 20 includes Examples 18 and 19 and specifies that the electrodebase includes about 5 to about 80 weight percent radiopaque agent, about1 to about 50 weight percent elutable drug component and a balancepolyetheretherketone.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a combined cutaway and perspective view of an implantablemedical device and lead in accordance with an embodiment of the presentinvention.

FIG. 2 is a side elevation view of the lead of FIG. 1.

FIG. 3 is a partial cross-sectional view of the lead of FIG. 1.

FIG. 4 is a side elevation view of a portion of a passive fixation leadin accordance with an embodiment of the present invention.

FIG. 5 is a perspective view of an electrode base and electrode usefulin the passive fixation lead of FIG. 4 in accordance with an embodimentof the present invention.

FIG. 6 is a cross-sectional view of the electrode base and electrode ofFIG. 5.

While the invention is amenable to various modifications and alternativeforms, specific embodiments have been shown by way of example in thedrawings and are described in detail below. The intention, however, isnot to limit the invention to the particular embodiments described. Onthe contrary, the invention is intended to cover all modifications,equivalents and alternatives falling within the scope of the inventionas defined by the appended claims.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of an implantable CRM system 10. The CRMsystem 10 includes a pulse generator 12 and a cardiac lead 14. The lead14 operates to convey electrical signals between the heart 16 and thepulse generator 12. The lead 14 has a proximal region 18 and a distalregion 20. The lead 14 includes a lead body 22 extending from theproximal region 18 to the distal region 20. The proximal region 18 iscoupled to the pulse generator 12 and the distal region 20 is coupled tothe heart 16. The distal region 20 includes an extendable/retractablefixation helix 24, which locates and/or secures the distal region 20within the heart 16.

The pulse generator 12 is typically implanted subcutaneously within animplantation location or pocket in the patient's chest or abdomen. Thepulse generator 12 may be any implantable medical device known in theart or later developed, for delivering an electrical therapeuticstimulus to the patient. In various embodiments, the pulse generator 12is a pacemaker, an implantable cardioverter/defibrillator (ICD), acardiac resynchronization therapy (CRT) device configured forbi-ventricular pacing, and/or includes combinations of pacing, CRT, anddefibrillation capabilities.

The lead body 22 can be made from any flexible, biocompatible materialssuitable for lead construction. In various embodiments, the lead body 22is made from a flexible, electrically insulative material. In oneembodiment, the lead body 22 is made from silicone rubber. In anotherembodiment, the lead body 22 is made from polyurethane. In variousembodiments, respective segments of the lead body 22 are made fromdifferent materials, so as to tailor the lead body characteristics toits intended clinical and operating environments. In variousembodiments, the proximal and distal ends of the lead body 22 are madefrom different materials selected to provide desired functionalities.

As is known in the art, the heart 16 includes a right atrium 26, a rightventricle 28, a left atrium 30 and a left ventricle 32. It can be seenthat the heart 16 includes an endothelial inner lining or endocardium 34covering the myocardium 36. In some embodiments, as illustrated, thefixation helix 24, located at the distal region 20 of the lead,penetrates through the endocardium 34 and is imbedded within themyocardium 36. In one embodiment, the CRM system 10 includes a pluralityof leads 14. For example, it can include a first lead 14 adapted toconvey electrical signals between the pulse generator 12 and the rightventricle 28 and a second lead (not shown) adapted to convey electricalsignals between the pulse generator 12 and the right atrium 26.

In the illustrated embodiment shown in FIG. 1, the fixation helix 24penetrates the endocardium 34 of the right ventricle 28 and is embeddedin the myocardium 36 of the heart 16. In some embodiments, the fixationhelix 24 is electrically active and thus can be used to sense theelectrical activity of the heart 16 and/or to apply a stimulating pulseto the right ventricle 28. In other embodiments, the fixation helix 24is not electrically active. Rather, in some embodiments, othercomponents of the lead 14 are electrically active.

FIG. 2 is an isometric illustration of the lead 14. A connector assembly40 is disposed at or near the proximal region 18 of the lead 14 while adistal assembly 42 is disposed at or near the distal region 20 of thelead 14. Depending on the functional requirements of the CRM system 10(see FIG. 1) and the therapeutic needs of a patient, the distal region20 can include one or more electrodes. In the illustrated embodiment,the distal region 20 includes a pair of coil electrodes 44 and 45 thatcan function as shocking electrodes for providing a defibrillation shockto the heart 16.

In various embodiments, the lead 14 can include only a single coilelectrode. In various other embodiments, the lead 14 includes one ormore ring electrodes (not shown) along the lead body 22 in lieu of or inaddition to the coil electrodes 44, 45. When present, the ringelectrodes operate as relatively low voltage pace/sense electrodes. Inshort, a wide range of electrode combinations can be incorporated intothe lead 14 within the scope of the various embodiments of the presentinvention.

The connector assembly 40 includes a connector 46 and a terminal pin 48.The connector 46 is configured to be coupled to the lead body 22 and isconfigured to mechanically and electrically couple the lead 14 to aheader on the pulse generator 12 (see FIG. 1). In various embodiments,the terminal pin 48 extends proximally from the connector 46 and in someembodiments is coupled to a conductor member (not visible in this view)that extends longitudinally within the lead body 22 and which isrotatable relative to the lead body 22 such that rotating the terminalpin 48 (relative to the lead body 22) causes the conductor member torotate within the lead body 22 as well. In some embodiments, theterminal pin 48 includes an aperture extending therethrough, and theconductor member defines a longitudinal lumen in communication with theaperture. When present, the aperture and/or conductor lumen areconfigured to accommodate a guide wire or an insertion stylet fordelivery of the lead 14.

In some embodiments, the distal assembly 42 includes a housing 50,within which the fixation helix 24 is at least partially disposed. Insome embodiments, the housing 50 includes or accommodates a mechanismthat enables the fixation helix 24 to move distally and proximallyrelative to the housing 50. In some embodiments, the housing 50 canaccommodate or include structure that limits distal travel of thefixation helix 24 (relative to the housing 50). As noted above, thefixation helix 24 operates as an anchoring means for anchoring thedistal region 20 of the lead 14 within the heart 16. In someembodiments, the fixation helix 24 is electrically active, and is alsoused as a pace/sense electrode. In some embodiments, the fixation helix24 is made of an electrically conductive material such as Elgiloy,MP35N, tungsten, tantalum, iridium, platinum, titanium, palladium, orstainless steel, as well as alloys of any of these materials. In someembodiments, the fixation helix 24 is made of a non-electricallyconductive material which includes polymeric materials such aspolyetheretherketone (PEEK), polyethersulfone (PES), polyimide (PI),polyamide (PA), liquid crystal polymer (LCP), polyethylene terephthalate(PET), polybutylene terephthalate (PBT), polyurethane (PU),polypropylene (PP) and any combinations of these polymers, and ceramics.

FIG. 3 illustrates an embodiment of a lead including distal assembliesin accordance with the present invention. FIG. 3 is a partialcross-section of the lead 14 that include the distal assembly 42. In theillustrated embodiment, the fixation helix 24 is electrically active soas to be operable as a pace/sense electrode.

As shown in FIG. 3, the housing 50 includes a distal region 52 and aproximal region 54. The housing 50 has an inner surface 53. The housing50 is, in general, relatively rigid or semi-rigid. In some embodiments,the housing 50 can be formed via injection molding. In otherembodiments, the housing 50 can be formed via a machining process. Insome embodiments, the housing 50 can include a threaded portion 80 thatinteracts with a cooperating threaded portion 82 formed in an end of thelead body 22. In some embodiments, the housing 50 can have an outersurface 84 having a largely uniform cross-sectional diameter by virtueof not having to incorporate separate fluoro rings and/or drug collars,as will be discussed in greater detail.

In some embodiments, the housing 50 is made of a non-electricallyconductive material which includes polymeric material such aspolyetheretherketone (PEEK), polyethersulfone (PES), polyimide (PI),polyamide (PA), liquid crystal polymer (LCP), polyethylene terephthalate(PET), polybutylene terephthalate (PBT), polyurethane (PU), andpolypropylene (PP) and any combinations of these polymers as well asceramics. In some embodiments, the housing 50 is cast or molded frompolyetheretherketone (PEEK) that incorporates one or more radiopaqueagents as well as one or more elutable drug components.

One or more radiopaque agents can be dispersed within the polymericmaterial in order to provide the housing 50 with a desired level ofvisibility when viewed using fluoroscopic techniques during and afterimplantation without requiring a separate fluoro ring. One or moreelutable drug components may be dispersed within the polymeric materialin order to provide a time-released dosage of a steroid or anotheranti-inflammatory agent to the tissue to be stimulated, e.g., the hearttissue in which the electrically active fixation helix 24 is implantedwithout requiring a separate drug collar.

In some embodiments, the housing 50 can be formed from an at leastsubstantially homogenous mixture of the radiopaque agent, the elutabledrug component and the polymeric material. In some embodiments, thepolymeric material is PEEK. As used herein, “substantially homogenous”may be defined as the composition of the bulk mixture, or thecomposition of an article formed from the mixture, varying by less thanabout ten percent, regardless of where in the mixture (or the article)the composition is sampled.

In some embodiments, the housing 50 can be formed from a polymericmixture that includes about 1 to about 80 weight percent of a radiopaqueagent and about 15 to about 50 weight percent of an elutable drugcomponent, with the balance being the polymeric material. It will beappreciated that in these compositional ranges, relatively small amountsof additives such as fillers, antioxidants, colorants, conductive agentsand processing aids may be included, and can be part of the polymericmaterial portion of the composition.

In some embodiments, the housing 50 can be formed from a polymericmixture that includes about 30 to about 70 weight percent of aradiopaque agent and about 10 to about 35 weight percent of an elutabledrug component, with the balance being PEEK. In some embodiments, thehousing 50 can be formed from a polymeric mixture that includes about 40to about 60 weight percent of a radiopaque agent and about 15 to about25 weight percent of an elutable drug component, with the balance beingthe polymeric material.

A variety of different radiopaque agents can be used. Illustrative butnon-limiting examples of suitable radiopaque agents include bariumsulfate, barium trioxide, tungsten, platinum, iridium, and alloysthereof. In some embodiments, a single radiopaque agent can be used. Insome embodiments, combinations of two or more distinct radiopaque agentscan be combined into the polymeric material.

A variety of different elutable drug components can be used. In this, anelutable drug component is a drug or drug precursor that is able todiffuse through and thus elute from the surface of the polymericmaterial. In some embodiments, the elutable drug component can be asteroid. Illustrative but non-limiting examples of suitable steroidsinclude dexamethasone, betamethasone, paramethasone, beclomethasone,clobetasol, triamcinolone, prednisone, prednisolone, and derivativesthereof. In some embodiments, a single steroid can be used. In someembodiments, combinations of two or more distinct steroids can becombined into the polymeric material.

As shown, the distal assembly 42 includes a coupler 58. In someembodiments, the coupler 58 is formed of a metallic material and isconfigured to move longitudinally and/or rotationally with respect tothe housing 50. The coupler 58 includes a distal portion 60, a proximalportion 62 and a central portion 64. As shown, the fixation helix 24 isconnected to the distal portion 60 of the coupler 58. In someembodiments, as illustrated, the distal portion 60 may have a relativelysmaller diameter (relative to at least part of the central portion 64)that is configured to accommodate the fixation helix 24.

In some embodiments, as illustrated, the central portion 64 of thecoupler 58 includes a sealing groove 66 that is configured toaccommodate an annular seal 68. The sealing groove 66 has a bottomsurface 70 that provides a surface for the annular seal 68 to seatagainst. The annular seal 68 is configured to provide a substantiallyfluid-tight seal between the coupler 58 and the inner surface 53 of thehousing 50 while minimizing frictional forces caused by the annular seal68. In some embodiments, the lead 14 can include one or more otherseals, and thus may not include the annular seal 68 or the sealinggroove 66.

The fixation helix 24 has a distal region 71 and a proximal region 72.The proximal region 72 is secured to the distal portion 60 of thecoupler 58. One or more attachment methods are used to secure thefixation helix 24 to the coupler 58. In some embodiments, the proximalregion 72 of the fixation helix 24 is welded or soldered onto the distalportion 60 of the coupler 58. In some embodiments, the proximal region72 of the fixation helix 24 has an inner diameter that is less than anouter diameter of the distal portion 60 of the coupler 58, and thus isheld in place via compressive forces. In some embodiments, multipleattachment methods are used.

A conductor member 74 is secured to the proximal portion 62 of thecoupler 58, and extends proximally through the lead body 22 to theconnector assembly 40. In some embodiments, the conductor member 74includes or is otherwise formed from a metallic coil. The coupler 58provides an electrical connection between the conductor member 74 andthe fixation helix 24. In the connector assembly 40, the conductormember 74 is coupled to the terminal pin 48 such that rotation of theterminal pin 48 causes the conductor member 74 to rotate. As theconductor member 74 rotates, the coupler 58 and the fixation helix 24will also rotate. In some embodiments, the fixation helix 24 is rotatedvia a stylet that is inserted through an aperture that may be formedwithin the terminal pin 48 (FIG. 2). The distal assembly 42 isconfigured so that relative rotation of the coupler 58 and fixationhelix 24 relative to the housing 50 results in longitudinal translationof the coupler 58 and fixation helix 24 relative to the housing 50,thereby providing the extendable/retractable functionality of thefixation helix 24.

The particular arrangement illustrated for facilitating extension andretraction of the fixation helix 24 is exemplary only. In other words,any arrangement, whether now known or later developed, for providing theextendable/retractable functionality of the fixation helix 24 can beutilized in connection with the various embodiments of the presentinvention. In one embodiment, the lead 14 includes structures such asthose described and illustrated in co-pending and commonly assigned U.S.Patent Publication 2010/0305672, the disclosure of which is incorporatedby reference herein in its entirety. In other embodiments, a differentarrangement for extending and retracting the fixation helix 24 isutilized.

The preceding Figures illustrate an active fixation lead 14 thatincludes a housing 50. In some embodiments, both active and fixationleads may include an assembly that is from a combination of radiopaqueagent, elutable drug component and polymeric material. In someembodiments, as shown above, the assembly may be a housing that issecured to a lead and that accommodates a coupler and active fixationhelix therein. In some embodiments, as described with respect to FIGS. 4through 6, the aforementioned assembly can instead include a foilelectrode and an electrode base that is configured to support the foilelectrode.

FIG. 4 is a side elevation view of a distal portion of a passivefixation lead 100. The lead 100 includes a lead body 102 and a distaltip 104. One or more passive fixation wings 106 extend from the leadbody 102 and can be used to help secure the lead 100 within the desiredvasculature or location of the heart. In some embodiments, the lead body102, the distal tip 104, and the passive fixation wings 106 can beformed from any flexible, biocompatible materials suitable for leadconstruction, including flexible, electrically insulative materials.

In one embodiment, the lead body 102, distal tip 104 and/or passivefixation wings 106 are made from silicone rubber or polyurethane. Invarious embodiments, respective segments of the lead 100 are made fromdifferent materials, so as to tailor the lead body characteristics toits intended clinical and operating environments. In variousembodiments, the proximal and distal ends of the lead 100are made fromdifferent materials selected to provide desired functionalities.

As illustrated, the lead 100 also includes several electrodes 108. Whiletwo electrodes are illustrated, in some embodiments the lead 100 caninclude a single electrode 108. In other embodiments, the lead 100 caninclude three or more electrodes 108. The construction of the electrode108 is illustrated with respect to FIGS. 5 and 6, which illustrate theelectrode 108 as including an electrode base and a foil electrodesupported by the electrode base.

FIG. 5 is a perspective view of one of the electrodes 108 and FIG. 6 isa cross-sectional view taken along line 6-6 of FIG. 5. As illustrated,the electrode 108 includes an electrode base 110 and a foil electrode112. It will be appreciated that by including the electrode base 110 tosupport the foil electrode 112, a substantially thinner electrode can beused. In some embodiments, the electrode base 108 can be considered asincluding a first region 114 having a first diameter D1 and a secondregion 116 having a second diameter D2 that is less than the firstdiameter D1. In some embodiments, as illustrated, the difference betweenD1 and D2 represents a thickness of the foil electrode 112. In someembodiments, the foil electrode 112 can include structure (notillustrated) that permits the foil electrode 112 to be electricallycoupled to a conductor extending through the lead 100.

As discussed above with respect to the housing 50, the electrode base110 can, in some embodiments, be formed from an at least substantiallyhomogenous mixture of radiopaque agent, elutable drug component andPEEK. The specific radiopaque agents that can be used in forming theelectrode base 110 are the same as those discussed with respect to thehousing 50. The specific elutable drug components are the same as thosediscussed with respect to the housing 50.

In some embodiments, the electrode base 110 can be formed from apolymeric mixture that includes about 20 to about 80 weight percent of aradiopaque agent and about 5 to about 40 weight percent of an elutabledrug component, with the balance being a polymeric material such asPEEK. It will be appreciated that in these compositional ranges,relatively small amounts of additives such as fillers, antioxidants,colorants, conductive agents and processing aids may be included and canbe part of the polymeric material portion of the composition.

In some embodiments, the electrode base 110 can be formed from apolymeric mixture that includes about 30 to about 70 weight percent of aradiopaque agent and about 10 to about 35 weight percent of an elutabledrug component, with the balance being a polymeric material such asPEEK. In some embodiments, the electrode base 110 can be formed from apolymeric mixture that includes about 40 to about 60 weight percent of aradiopaque agent and about 15 to about 25 weight percent of an elutabledrug component, with the balance being a polymeric material such asPEEK.

The foil electrode 112 can be made of any suitable conductive materialsuch as, but not limited to, MP35N, tungsten, tantalum, iridium,platinum, titanium, palladium, stainless steel, as well as alloys of anyof these materials. As noted, the foil electrode 112 can be relativelythin, with a thickness about equal to the difference between D1 and D2.In some embodiments, the foil electrode 112 can have a thickness that isin the range of about 0.0001 inches to about 0.005 inches. In someembodiments, the foil electrode 112 can have a thickness of about 0.001inches.

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. For example, while the embodiments described above refer toparticular features, the scope of this invention also includesembodiments having different combinations of features and embodimentsthat do not include all of the described features. Accordingly, thescope of the present invention is intended to embrace all suchalternatives, modifications, and variations as fall within the scope ofthe claims, together with all equivalents thereof.

We claim:
 1. An implantable lead comprising: a flexible body extendingbetween a proximal end and a distal end; a connector assembly secured tothe proximal end for coupling the lead to an implantable medical device,the connector assembly including a terminal pin rotatable relative tothe body; a conductor member disposed longitudinally within the body andcoupled to the terminal pin, the conductor member rotatable relative tothe body; and a distal assembly coupled to the distal end of the bodyand including: a housing having a distal region and a proximal region,the proximal region fixedly coupled to the distal end of the body, thehousing formed from a polymeric material; a radiopaque agent dispersedwithin the polymeric material forming the housing; an elutable drugcomponent dispersed within the polymeric material forming the housing; acoupler rotatably disposed within the housing, the coupler having aproximal end and a distal end, the proximal end connected to theconductor member; and a helical electrode fixedly secured to thecoupler; wherein the terminal pin is rotatably engaged with the couplervia the conductor member such that rotation of the terminal pin causesthe coupler and the helical electrode to rotate and therefore translaterelative to the housing.
 2. The implantable lead of claim 1, wherein thepolymeric material comprises polyetheretherketone.
 3. The implantablelead of claim 1, wherein the housing comprises an at least substantiallyhomogenous mixture of radiopaque agent, elutable drug component andpolyetheretherketone.
 4. The implantable lead of claim 1, wherein thepolymeric material forming the housing comprises: about 5 to about 80weight percent of the radiopaque agent; about 1 to about 50 weightpercent of the elutable drug component; and a balancepolyetheretherketone.
 5. The implantable lead of claim 1, wherein thepolymeric material forming the housing comprises: about 30 to about 70weight percent of the radiopaque agent; about 10 to about 35 weightpercent of the elutable drug component; and a balancepolyetheretherketone.
 6. The implantable lead of claim 1, wherein thepolymeric material forming the housing comprises: about 40 to about 60weight percent of the radiopaque agent; about 15 to about 25 weightpercent of the elutable drug component; and a balancepolyetheretherketone.
 7. The implantable lead of claim 1, wherein theradiopaque agent comprises one or more of barium sulfate, bariumtrioxide, tungsten, platinum, iridium and alloys thereof.
 8. Theimplantable lead of claim 1, wherein the elutable drug componentcomprises a steroid.
 9. An implantable lead configured to carry anelectrical signal, the implantable lead comprising: a flexible bodyextending between a proximal portion and a distal portion, the bodyconfigured to carry an electrical signal from the proximal portion tothe distal portion; and an assembly coupled to the distal portion of theflexible body, the assembly formed from an at least substantiallyhomogenous combination of polyetheretherketone, radiopaque agent andelutable drug component.
 10. The implantable lead of claim 9, whereinthe assembly comprises a housing extending from the distal portion ofthe flexible body, the implantable lead further comprising a couplerdisposed within the housing and a fixation helix secured to the coupler.11. The implantable lead of claim 9, wherein the implantable leadfurther comprises a foil electrode and the assembly comprises anelectrode base configured to support the foil electrode.
 12. Theimplantable lead of claim 11, wherein the electrode base has an outersurface having a first region and a second region, the first regionsupporting the foil electrode and the second region uncovered to permitdrug elution from the electrode base.
 13. The implantable lead of claim9, wherein the assembly comprises: about 20 to about 80 weight percentof the radiopaque agent; about 5 to about 40 weight percent of theelutable drug component; and a balance polyetheretherketone.
 14. Theimplantable lead of claim 9, wherein the assembly comprises: about 30 toabout 70 weight percent of the radiopaque agent; about 10 to about 35weight percent of the elutable drug component; and a balancepolyetheretherketone.
 15. The implantable lead of claim 9, wherein theassembly comprises: about 40 to about 60 weight percent of theradiopaque agent; about 15 to about 25 weight percent of the elutabledrug component; and a balance polyetheretherketone.
 16. The implantablelead of claim 9, wherein the radiopaque agent comprises one or more ofbarium sulfate, barium trioxide, tungsten, platinum, iridium and alloysthereof.
 17. The implantable lead of claim 9, wherein the elutable drugcomponent comprises one or more of dexamethasone, betamethasone,paramethasone, beclomethasone, clobetasol, triamcinolone, prednisone,prednisolone and derivatives thereof.
 18. An implantable lead configuredto carry an electrical signal, the implantable lead comprising: aflexible body extending between a proximal portion and a distal portion,the body configured to carry an electrical signal from the proximalportion to the distal portion; an electrode base coupled to the distalportion of the flexible body, the electrode base formed from an at leastsubstantially homogenous combination of polyetheretherketone, radiopaqueagent and elutable drug component; and a foil electrode supported by aportion of the electrode base.
 19. The implantable lead of claim 18,wherein the electrode base has an outer surface having a first regionand a second region, the first region having a first diameter andsupporting the foil electrode and the second region having a seconddiameter greater than the first diameter, the second region uncovered topermit drug elution from the electrode base.
 20. The implantable lead ofclaim 18, wherein the electrode base comprises: about 20 to about 80weight percent of the radiopaque agent; about 5 to about 40 weightpercent of the elutable drug component; and a balancepolyetheretherketone.